The Greater Caucasus Glacier Inventory (Russia/Georgia/Azerbaijan)

Abstract

Abstract. While there are a large number of glaciers in the Greater Caucasus, the region is not fully represented in modern glacier databases with previous incomplete inventories. Here, we present an expanded glacier inventory for this region over the 1960–1986–2014 period. Large scale topographic maps and satellite imagery (Landsat 5, Landsat 8 and ASTER) were used to conduct a remote sensing survey of glacier change in the Greater Caucasus mountains. Glacier margins were mapped manually and reveal that, in 1960, the mountains contained 2349 glaciers, with a total glacier surface area of 1674.9 ± 35.2 km2. By 1986, glacier surface area had decreased to 1482.1 ± 32.2 km2 (2209 glaciers), and by 2014, to 1193.2 ± 27.0 km2 (2020 glaciers). This represents a 28.8 ± 2.2 % (481 ± 10.6 km2) reduction in total glacier surface area between 1960 and 2014 and a marked acceleration in the rate of area loss since 1986. Analysis of possible controls suggest that the general decreases in both glacier area and number for the period 1960–2014 are directly due to general increase in temperature, especially in summer (June–July–August), although the response of individual glaciers was modulated by other factors, including glacier size, elevation, rock structure, exposition, morphological type and debris cover. This new glacier inventory can be used as a basis dataset for future studies including glacier change assessment.

Supraglacial debris cover assessment in the Caucasus Mountains, 1986-2000-2014

“…10 5a). The benefit of local knowledge and GPS points can be seen in Figures 5b and 5c where both cloud and shadow hidden areas of glacier cover which were recognized in the Tielidze & Wheate (2017) outlines as a result of field measurements. Compared with a simple 4/6 ratio and the Alifu et al (2015) method, this integrated geomorphometric parameter technique encompassing proximity and texture values provides a more accurate representation of glaciers in the Greater 15 Caucasus.…”

“…After the creation of clean glacier outlines using the OLI 4/6 or TM 3/5 ratio, extra polygons (late lying snow, shadows) were deleted and corrected relative to the 1986, 2000 and 2014 manual outlines (except for the debris covered area) from the latest glacier inventory (Tielidze and Wheate, 2017). This semi-automated technique might be faster (Tiwari et al, 2016) than manual delineation at visualizing the bare-ice extent, but it was important to manually correct the semi-automated outlines of up-glacier boundaries of the debris-covered ice as accurately as possible in order to assess subtle changes in the extent over time (e.g.…”

“…This was then combined with the previous clean glacier ice ratio image to form glacier outlines with debris. To remove excess misclassified polygons manual adjustments were performed using the most recent Caucasus 15 glacier inventory for authentication (Tielidze and Wheate, 2017) and by exporting the outlines to KML and verifying them with 3D topography in Google Earth. The work flow chart is shown in Figure 2, incorporating the recently available ALOS 30 m Global DSM.…”

“…Technical errors can be mostly ignored if the satellite image has been accurately orthorectified, which was the case for Landsat images provided by USGS (e.g. Tielidze, 2016;Tielidze and Wheate, 2017). Interpretation errors mostly depend on how 'glacier' is defined for the purposes of inventory compilation, and thus are difficult to evaluate.…”

Jumping the barrier: Does a glacier tongue affect species distribution along the elevation gradient in the subnival and nival belts? A case study on Mt. Kazbegi, Georgia, Central Great Caucasus Mountains

“…There are 2020 glaciers in the Great Caucasus Mountains, with a surface of 1193.2 ± 54.0 km² and mean elevation of 3506 m a.s.l. (Tielidze & Wheate 2018). Glaciers can affect plant distributions along the gradients in mountains in various ways.…”